Finding the Period of a Squared Trig FunctionDate: 08/28/2006 at 22:54:11 From: robyn Subject: Determining the period of trigonometric equations How do you find the period of a cosine equation when the cosine is squared? For example, 3 - 2cos^2(pi(x)/3). Every attempt I've made has given me a period of 2pi, and I know it is supposed to be 3. I tried breaking it into cos(x) * cos(pi/3), but that is not correct. I cannot figure out how the squared affects the graph. Date: 08/29/2006 at 10:13:33 From: Doctor Fenton Subject: Re: Determining the period of trigonometric equations Hi Robyn, Thanks for writing to Dr. Math. You need to use one of the Double Angle identities (or a Half Angle identity, depending upon your point of view) to rewrite cos^2(t) as a trigonometric function to the first power, instead of being squared. Then you should be able to determine the period. If you are not familiar with the identities, they are listed on Trig Identities http://mathforum.org/dr.math/faq/formulas/faq.trig.html#identities If you have any questions or need more help, please write back and show me what you have done, and I will try to offer further suggestions. - Doctor Fenton, The Math Forum http://mathforum.org/dr.math/ Date: 08/29/2006 at 18:20:56 From: robyn Subject: Thank you (Determining the period of trignomonic equations) THANK YOU SOOO MUCH! I have been working on an AP Calc packet for days and could not figure out that problem. Thanks a million times! |
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